Internal-combustion Forklift Inlet Pressure Loss Of The Muffler Characteristic Analysis And Optimization Research

Internal combustion forklift is an important logistics operations tool,mainly used in the production workshop,port and other materials handling operations occasions.At present,China's forklift noise standard is issued when the calibration power is less than 55 kw,the sound power level is 104dB(A),the noise limit is85 dB,because the forklift for a long time continuous work,making the noise on the driver's health has a different degree of damage,therefore,the researchers are concerned about the internal combustion forklift noise reduction design.At present,the noise reduction design of the exhaust end of the internal combustion engine-exhaust muffler,has been more research and application,and in the internal combustion engine at the end of the noise reduction research less,so to carry out the inlet end muffler mechanism to reduce the forklift work noise,improve the operator's comfort has important engineering significance.In this paper,the internal combustion forklift intake muffler as the object,the use of Virtual.Lab on the intake muffler for sound field modeling and simulation of its acoustic performance evaluation,analysis of the intake muffler internal increase in the baffle,perforation and insertion tube after the transfer loss,It is found that the change of perforation rate has no obvious effect on the change trend of transmission loss,but the sound waves in the flow through the holes and obstacles,will occur in different degrees of diffraction and reflection,change the perforation rate can change the acoustics performance of muffler at different frequency band to achieve the best.According to the study of 700Hz-900 Hz band,the design of the perforation rate select 12%.Then,the CFD numerical calculation method is used to simulate the intake muffler,and the internal pressure field distribution and velocity field distribution were analyzed.The results show that the flow rate from the inlet end of the muffler along the pipe to the outlet end is faster,the farther away from the pipeline,the smaller the flow rate.The flow rate is at thebaffle and the outlet,and the inlet flow rate has some mathematical relationship with the inlet and outlet pressure and the pressure loss.The perforation of the perforated pipe and the baffle Which facilitates the flowability of the gas inside the cavity and improves the aerodynamic performance.This paper presents two structural improvement schemes: ?.Design of dual-cavity muffler by adding baffle and perforating tube;?.To further optimize the design of the four-cavity complex muffler.The results show that the acoustic performance evaluation and fluid modeling simulation of the two schemes are better than those of the original muffler.The pressure loss of the scheme is larger than that of the ? scheme,reaching 8.75 kpa,but much lower than the target value of 12.75 kpa,The acoustic performance is better than the ? scheme,? program for the four-chamber design structure,and the perforation of the small hole group,the air flow can play a role in the divergence and diffusion,and the internal pressure changes within the level,there is no obvious mutation,regardless of acoustic performance,or aerodynamic performance are dominant.At the end of this paper,the experimental scheme of ? scheme is verified,and the optimization result of ? scheme can meet the design requirements.